Chinese officials appear to have retreated from their controversial plan to install an internet filtering system on computers in the country.

The industry and information technology minister, Li Yizhong, said today that the notion that the Green Dam programme would be required on every new computer was “a misunderstanding” spawned by poorly written regulations.

He said all public computers in schools and internet cafes must install the software – but the government “respected the choice of individuals who do not install it”. He said: “Those who overstated and politicised the issue, or even attacked China’s internet regulation, are irresponsible,” and added that pornography was the main target of the software.

Its initial plans met with fierce opposition when they were announced, with many internet users fearing that the software – which blocks pornographic, violent and politically sensitive content – would also be used to monitor behaviour, curb access to information and track users.

At first it appeared that the campaign, which was backed by the US government, was gaining ground. However last month, hours before the programme was due to be implemented, officials briefed that there would be a delay, but the plans would eventually go ahead.

Today’s announcement appears to make that suspension permanent, with Li saying the government would neither require the programme to come pre-installed on new computers, nor force computer makers to include the programme on a CD with optional software.

New government guidance has been published urging civil servants to use the micro-blogging site Twitter. Launched on the Cabinet Office website, the 20-page document is calling on departments to “tweet” on “issues of relevance or upcoming events”.

The website is already used by Downing Street, the Foreign Office and many individual MPs. Neil Williams, of the Department for Business, Innovation and Skills (BIS), published the “template” strategy.

Writing on the Cabinet Office’s digital engagement blog, Mr Williams – who is BIS’s head of corporate digital channels – conceded that 20 pages was a “a bit over the top for a tool like Twitter” but added “I was surprised by just how much there is to say – and quite how worth saying it is.”

The template had been written for BIS to consider using Twitter but could be used by other departments, he said. Publishing tweets, replying to incoming messages and monitoring the account would take less than an hour a day, according to the strategy.

Tweets should also be limited to issues of relevance or upcoming events rather than just campaign messages, and insights from ministers are encouraged.

A widespread computer attack has hit several US government agencies while some South Korean government websites also appear to be affected.

The US Treasury Department, Secret Service, Federal Trade Commission and Transportation Department were all hit by the attack that started on July 4. In South Korea, the presidential Blue House and Defence Ministry, National Assembly appear to have been hit.

US officials have not released details of the attack. Ben Rushlo, head of internet technologies at web performance firm Keynote Systems described it as a “massive outage”.

Amy Kudwa, a spokeswoman for the Department of Homeland Security said the body’s US Computer Emergency Readiness Team (CERT) told federal departments about the issue and of steps “to mitigate against such attacks”.

Recently the US homeland security secretary Janet Napolitano told the BBC that protecting against virtual attacks was a matter of “great concern” and something the US was “moving forward with great alacrity”.

The attacks in South Korea seemed to be connected to the attack of US government services, said Ahn Jeong-eun, a spokesperson at Korea’s Information Security Agency. South Korea’s Yonhap News Agency is reporting that North Korea may be behind Tuesday’s cyber attack.

The world’s store of digital content is now the equivalent of one full top-of-the-range iPod for every two people on the planet, following the explosion of social networking sites, internet-enabled mobile phones and government surveillance.

At 487bn gigabytes (GB), if the world’s rapidly expanding digital content were printed and bound into books it would form a stack that would stretch from Earth to Pluto 10 times.

As more people join the digital tribe – increasingly through internet-enabled mobile phones – the world’s digital output is increasing at such a rate that those stacks of books are rising quicker than Nasa’s fastest space rocket.

The digital universe is expected to double in size over the next 18 months, according to the latest research. About 70% of the information in the digital universe is created by individuals and includes phone calls, emails, photos, online banking transactions or postings on social networking sites.

Unnecessary duplication in mobile phone networks is wasting an “enormous” amount of energy, the Green Party has claimed.

In a report released last week, the party said there are at least 50,000 base stations across the UK, many of which belong to rival companies and serve the same areas. The party is calling for government regulation to force operators to create one “super-network”, which it estimates could save 300 gigawatt hours (GWh) a year, the equivalent of the annual electricity use of nearly 70,000 homes.

The UK is covered by five virtually independent networks due to the government’s early attempts to ensure competition in the industry. James Page, industry policy adviser to the Green Party, said: “The government wanted competition, but you can achieve competition without necessarily having a separate network each. The best hope is in government requiring Ofcom to begin considering environmental and energy issues, because at the moment it doesn’t.”

The time is ideal for the government to step in, said the party, because of the impending digital television switchover. Ofcom will auction off the frequency currently used by analogue television broadcasts in 2010, handing it over for use by mobile operators. When new masts are built to take advantage of the extra spectrum, they could be built in a partnership, suggests the report.

The UK’s electronic intelligence agency has taken the unusual step of issuing a statement to deny it will track all UK internet and online phone use.

Government Communications Headquarters (GCHQ) said it was developing tracking technology but “only acts when it is necessary” and “does not spy at will”.

The denial follows the home secretary scrapping plans for a single government database for all communications. Jacqui Smith said instead firms should record all people’s internet contacts.

In the statement, GCHQ said one of its “greatest challenges is maintaining our capability in the face of the growth in internet-based communications. We must reinvest continuously to keep up with the methods that are used by those who threaten the UK and its interests.”

But the agency added: “GCHQ is not developing technology to enable the monitoring of all internet use and phone calls in Britain, or to target everyone in the UK. Similarly, GCHQ has no ambitions, expectations or plans for a database or databases to store centrally all communications data in Britain.”

The Home Office has been accused of colluding with online ad firm Phorm on “informal guidance” to the public on whether the company’s service is legal.

E-mails between the ministry and Phorm show the department asking if the firm would be “comforted” by its position. The messages show Phorm making changes to the guidance sought by the ministry.

Lib Dem Home Affairs spokeswoman Baroness Sue Miller, who has questioned the Home Office about Phorm, said the e-mails were “jaw dropping”. A Home Office spokesperson said the suggestion of “collusion” was totally unfounded.

“We have repeatedly said since these documents were released a year ago that the Government has not endorsed Phorm or its technology. We are committed to protecting the privacy of UK consumers and will ensure any new technology of this sort is applied in an appropriate and transparent manner, in full accordance with the law and with proper regulation from the appropriate authority.”

The e-mail exchanges were released under a Freedom of Information (FOI) Act request made by a member of the public and sent to the BBC.